Lamp.



G. A. MACBETH.

LAMP.

APPLICATION FILED APB.18, 1910.

1, 1 1 9,848. Patented Dec. 8, 1914.

INVENTOR GEORGE A. MACBETH, 0F PITTSBURGH, PENNSYLVANIA.

LAMP.

Specification of Letters Patent.

Patented Dec. 8, 1914.

Application filed April 18, 1910. Serial No. 556,155.

To, all whom it may concern Be it known that I, GEORGE A. MACBETH, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Lamps, of which the following is a specification.

The invention relates to vehicle lamps and particularly to the lens construction. It has for its principal objects the provision of an improved form of ridged lens, and the provision of an improved construction of lens and lamp casing whereby the lens is supported removably in position. One embodiment of the invention is illustrated in the accompanying drawings wherein,

Figure 1 isa section through the lamp, and V Figure 2 is a plan view of the rear face of the glass or lens employed.

Referring to Fig. 1 of the drawing, 1 is a casing of the lamp which may be of any approved form; 2 is a source of illumination; 3 is a reflector placed to the rear of the source of illumination; 4 is the lens or glass employed; and 5 is a snap ring for holding the lens in position.

The rear face of the glassv is provided with a plurality of transverse parallel refleeting ridges 6, 7, 8, 9, 10, 11 and 12, which ridges have their inclined faces at varying angles, so that the rays of light passing through these different ridges may emerge from the lens in substantially parallel relation and bent slightly downward. As indicated in Fig. 2 these ridges do not extend entirely across the rear face of the lens, but terminate at some distance from such edge at the plane annulus 13. At the outer edge of this annulus is a head 14 extending entirely around the periphery of the lens. This bead 14 fits against a stop or holding portion 15 formed by the lamp casing, and such casing is provided to the front of the stop portion 15 with a snap ring receiving recess 16, so that when the parts are in the position indicated in Fig. 1 the lens is very securely held between the curved stop portion 15 and the snap ring 5.

The placing of the refracting ridges upon the inside of the glass is desirable as m'thls position the ridges are protected from inury, and the plain polished outer surface of the lens presents a better appearance than would be the case if the ridges were placed upon the outside face of the lens. The pro VlSlOIl of the plain annular portion at the ends of the ridges is also desirable as it permits this portion of the lens to fit tightly against the receiving portion of the lamp casing, thus giving a tight joint between the parts and a more secure support than is the case where the lamp casing is made to fit against the edges of the ridges themselves. Furthermore all the holding strain is removed from the ridges themselves and transferred to the edge of the lens which is stiffened and strengthened by means of the head 14. The head, in addition to strengthening the edge of the glass serves to give a more secure support for the lens than would be the case if a plain edge were employed. Other advantages incident to the construction will be apparent to those skilled in the art.-

Having" thus described my invention and and having a substantially plain annulus.

on its rear face and provided on sucn rear face with a plurality of transverse horizontal refracting ridges terminating at the said annulus, and a snap ring in the said recess.

2. In a vehicle lamp, a circular lens having one face plain and its other face provided with a head at its periphery, with aplain annulus inside such bead, and with a plurality of transverse parallel refracting ridges extending across the face and terminating at such plain annulus.

3. In a vehicle lamp, a casing provided with a fixed stop and with a snap ring recess spaced away therefrom, a lens having a plain front face fitting against the stop and having a substantially plain annulus on its rear face with a curved head at the outer edge thereof and also provided on ill horizontal retracting ridges terminating at such annulus, and snap ring circular in cross section in the said recess and lying to the outside of the center line of the bead whereby the bead tends to maintain the snap ring in position.

4; ine, vehicle lamp, a casing provided with a fixed stop, a movable stop spaced away therefrom, and a lens lying between the two stops and held thereby and having one'face substantially plain, and having on its other face a substantially plain annulus and a plurality of transverse horizontal retracting ridges terminating at the said ani GEO. A. MA CBETH.

. Witnesses:

PAUL SYNNEs'rVEDT, J. C. BRADLEY. 

